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0 <br /> - 4 - 14 September 2006 i <br /> concentration trend; hence the time needed to reach water quality objectives cannot be <br /> estimated from the existing data. Additional remediation may be required to reduce TPHg <br /> concentrations in groundwater and reach water quality objectives. <br /> The SJCEHD did not require that 1,2-DCA be sampled in soil and groundwater for closure of <br /> Case #1 (1991-97). The Case #2 soil confirmation sampling for the USTs removal in <br /> September 2002 also did not include sampling for 1,2-DCA. However, SJCEHD requested the <br /> 1,2-DCA groundwater analysis after the August 2002 USTs removal, and was notified in <br /> October 2002 that 1,2-DCA was detected in groundwater from existing monitoring wells. The <br /> SJCEHD opened Case #2 in November 2002 to determine the vertical and lateral extent of <br /> 1,2-DCA in soil and groundwater. A subsequent soil and groundwater investigation was <br /> conducted in 2004 and reported that 1,2-DCA was not detected in soil boring samples taken <br /> around the tank pit and offsite to the north and southwest. <br /> The following graph shows 1,2-DCA concentrations from October 2002 through January 2006 <br /> in MW-2. While Graph 3 shows the overall concentration trend from 2002 to 2006 is declining <br /> with time, subsequent data from January 2004 through January 2006 show an increasing <br /> concentration trend. Additional data are needed to evaluate whether the Site is a source of <br /> the 1,2-DCA detected in underlying groundwater. <br /> Graph 3 <br /> MW-2 1,2-DCA - <br /> 30 -- <br /> 25 v - ---- -- --- <br /> 20 - -- - -� <br />' rn 15 _- -- <br /> 10 -_� -�MW-2 1,2-DCA <br /> 5 - —Linear (MW-21,2-DCA) <br /> 0 , <br /> Off` Off` <br /> '3J� O°�t��� �Jc Oo��e� �J� Oo fie, <br /> date <br /> Figure 2 (enclosed) shows the extent of the known groundwater pollution in January 2006, <br /> with one exception: TPHg (280 pg/L) detected in March 2004 in the upgradient groundwater <br /> grab sample B-26 (not shown but 30 feet east of shown VW-6). And 1,2-DCA has been <br /> detected in groundwater from MW-1 through MW-3 across the Site. From 1994 to 2006, the <br /> downgradient groundwater direction varied from southeast to southwest. While grab <br /> groundwater sampling from boring B-27 showed no petroleum hydrocarbons detected 400 feet <br /> to the southeast of the Site, the extent of pollution to the northwest and south of the Site has <br />